U.S. patent number 10,064,124 [Application Number 14/915,829] was granted by the patent office on 2018-08-28 for communication device, network node, and computer program for communication and/or device-to-device operation in an out of coverage state.
This patent grant is currently assigned to Telefonaktiebolaget LM Ericsson (Publ). The grantee listed for this patent is Telefonaktiebolaget LM Ericsson (publ). Invention is credited to Muhammad Kazmi, Bengt Lindoff.
United States Patent |
10,064,124 |
Lindoff , et al. |
August 28, 2018 |
Communication device, network node, and computer program for
communication and/or device-to-device operation in an out of
coverage state
Abstract
A method of a communication device configured for cellular
communication and device-to-device, D2D, operation and operating in
an out-of-coverage, OoC, state is disclosed. The method comprises
determining whether a D2D operation is ongoing or imminent,
performing cell search according to a first rate when no D2D
operation is ongoing or imminent, and performing cell search
according to a second rate when D2D operation is ongoing or
imminent. A method is also disclosed where it is determined whether
the communication device is in one of an OoC and IC state, and a
cell search is adapted accordingly. A communication device and a
network node, a method for a network node, and computer programs
are also disclosed.
Inventors: |
Lindoff; Bengt (Bjarred,
SE), Kazmi; Muhammad (Bromma, SE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Telefonaktiebolaget LM Ericsson (publ) |
Stockholm |
N/A |
SE |
|
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Assignee: |
Telefonaktiebolaget LM Ericsson
(Publ) (SE)
|
Family
ID: |
55305002 |
Appl.
No.: |
14/915,829 |
Filed: |
February 5, 2016 |
PCT
Filed: |
February 05, 2016 |
PCT No.: |
PCT/EP2016/052526 |
371(c)(1),(2),(4) Date: |
March 01, 2016 |
PCT
Pub. No.: |
WO2016/124750 |
PCT
Pub. Date: |
August 11, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160360475 A1 |
Dec 8, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62113146 |
Feb 6, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
48/16 (20130101); H04W 76/14 (20180201); H04W
76/28 (20180201); H04W 4/80 (20180201); H04W
72/085 (20130101); H04W 76/27 (20180201); H04W
8/005 (20130101) |
Current International
Class: |
H04W
48/16 (20090101); H04W 72/08 (20090101); H04W
4/80 (20180101); H04W 76/27 (20180101); H04W
76/28 (20180101); H04W 76/14 (20180101); H04W
8/00 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2013130052 |
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Sep 2013 |
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WO |
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2014045832 |
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Mar 2014 |
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WO |
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2015063185 |
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May 2015 |
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WO |
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Other References
International Search Report and Written Opinion dated May 25, 2016
for PCT International Application Serial No. PCT/EP2016/052526,
International Filing Date--Feb. 5, 2016 consisting of 14-pages.
cited by applicant .
3GPP TSG-RAN WG1, R1-060105, Agenda item: 5.1.3.4, Source:
Ericsson, Title: "E-UTRA Cell Search", Document for Discussion and
Decision, Conference Location and Date: Helsinki, Finland, Jan.
23-25, 2006 consisting of 7-pages. cited by applicant .
3GPP TS 36.300 V11.2.0 (Jun. 2012) 3rd Generation Partnership
Project; Technical Specification Group Radio Access Network;
Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved
Universal Terrestrial Radio Access Network (E-UTRAN); Overall
Description; Stage 2 (Release 11) Jul. 2, 2012 consisting of
201-pages. cited by applicant .
3GPP TS 23.303 V12.3.0 (Dec. 2014) 3rd Generation Partnership
Project; Technical Specification Group Services and System Aspects;
Proximity-based services (ProSe); Stage 2 (Release 12) Dec. 17,
2014 consisting of 62-pages. cited by applicant .
3GPP TSG-RAN WG4 #74 R4-151126, Source: Ericsson, Qualcomm
Incorporated Title: "RRM requirements for ProSe", Conference
Location and Date: Athens, Greece, Feb. 9-13, 2015 consisting of
28-pages. cited by applicant .
Office Action dated Oct. 5, 2017 in related U.S. Appl. No.
15/031,038 consisting of 7-pages. cited by applicant .
3GPP_3GPP TR 22.803 V12.2.0 (Jun. 2013) 3rd Generation Partnership
Project; Technical Specification Group Services and System Aspects;
Feasibility study for Proximity Services (ProSe) (Release 12) Mar.
14, 2012 consisting of 45-pages. cited by applicant .
3GPP TSG-RAN WG1 Meeting #74, R1-133496, Agenda item: 7.2.8.1,
Source: Nokia, NSN, Title: D2D Synchronization--Out of Network
Coverage/Partial Network Coverage:, Document for Discussion and
Decision, Conference Location and Date: Barcelona, Spain, Aug. 23,
2013 consisting of 2-pages. cited by applicant .
International Search Report and Written Opinion dated Apr. 16, 2015
for related (not parent) PCT International Application Serial No.
PCT/EP2014/073266, International Filing Datet--Oct. 29, 2014
consisting of 13-pages. cited by applicant.
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Primary Examiner: Pham; Chi H
Assistant Examiner: Huang; Weibin
Attorney, Agent or Firm: Christopher & Weisberg,
P.A.
Claims
The invention claimed is:
1. A method of a communication device configured for cellular
communication and device-to-device, D2D, operation and operating in
an out-of-coverage, OoC, state, the method comprising: determining
whether a D2D operation is one of ongoing and imminent; performing
cell search according to a first rate when no D2D operation is one
of ongoing and imminent; and performing cell search according to a
second rate when D2D operation is one of ongoing and imminent, the
relation between the first rate and the second rate being such that
the second rate is higher than the first rate by a scaling
factor.
2. The method of claim 1, wherein the first rate and the second
rate define how often information about a cell to be searched
should be received and processed by the communication device.
3. The method of claim 1, further comprising, upon determining that
the D2D operation is ongoing: determining when the D2D operation
stops; starting a timer; and when the timer has elapsed, returning
to the determining whether a D2D operation is one of ongoing and
imminent.
4. The method of claim 1, wherein the second rate corresponds to
any of: a cell search rate used in an in-coverage, IC, state; a
discontinuous reception, DRX, cycle; and a rate preconfigured by
the radio access network.
5. The method of claim 1, wherein the out of coverage state
comprises `any cell selection state`.
6. The method of claim 5, wherein the `any cell selection state` is
a type of radio resource control, RRC, state where the
communication device is preconfigurable to perform D2D operation on
a side link of a preconfigured carrier.
7. The method of claim 1, wherein D2D operation is at least one of:
D2D transmission; D2D reception; Proximity service, ProSe, direct
communication; and ProSe direct discovery.
8. A method of a communication device configured for cellular
communication and device-to-device, D2D, operation and operating in
an out-of-coverage, OoC, state, the method comprising: determining
whether a D2D operation is one of ongoing and imminent; performing
cell search according to a first rate when no D2D operation is one
of ongoing and imminent; and performing cell search according to a
second rate when D2D operation is one of ongoing and imminent, the
first rate allows the communication device to identify a cell
within a first time period and the second rate allows the
communication device to identify a cell within a second time
period, where the first time period is larger than the second time
period.
9. The method of claim 8, wherein a time period where the
communication device identifies the cell within one of the first
and second time period is defined as a cell identification
delay.
10. A method of a communication device configured for cellular
communication and device-to-device, D2D, operation and operating in
an out-of-coverage, OoC, state, the method comprising: determining
whether a D2D operation is one of ongoing and imminent; performing
cell search according to a first rate when no D2D operation is one
of ongoing and imminent; and performing cell search according to a
second rate when D2D operation is one of ongoing and imminent, the
first rate and the second rate being used to search a cell within a
time duration equal to a first cell identification delay and a
second cell identification delay, respectively.
11. A communication device for operating with a cellular radio
access network and configured for device-to-device operation, the
communication device comprising: a receiver configured to receive
at least one signal from a controlling node of the cellular radio
access network for performing cell search; and a controller
configured to, when the communication device is in an out-of
coverage, OoC, state with relation to the controlling node, assign
a scheme for the cell searching such that the communication device
is configured to perform cell search according to a cell search
scheme where the controller is arranged to determine whether a D2D
operation is one of ongoing and imminent, wherein the communication
device is arranged to perform the cell search at a first rate when
no D2D operation is one of ongoing and imminent, and to perform the
cell search at a second rate when D2D operation is one of ongoing
and imminent, the relation between the first rate and the second
rate being such that the second rate is higher than the first rate
by a scaling factor.
12. The communication device of claim 11, wherein the first rate
and the second rate define how often information about a cell to be
searched should be received and processed.
13. The communication device of claim 11, wherein the controller is
configured to, upon determination that the D2D operation is
ongoing: determine when the D2D operation stops; start a timer; and
when the timer has elapsed, return to determine whether a D2D
operation is one of ongoing and imminent.
14. The communication device of claim 11, wherein the second rate
corresponds to any of: a cell search rate used in an in-coverage,
IC, state; a discontinuous reception, DRX, cycle; and a rate
preconfigured by the radio access network.
15. The communication device of claim 11, wherein the out of
coverage state comprises `any cell selection state`.
16. The communication device of claim 15, wherein the `any cell
selection state` is a type of radio resource control, RRC, state
where the communication device is preconfigurable to perform D2D
operation on a side link of a preconfigured carrier.
17. The communication device of claim 11, wherein D2D operation is
at least one of: D2D transmission; D2D reception; Proximity
service, ProSe, direct communication; and ProSe direct
discovery.
18. A communication device for operating with a cellular radio
access network and configured for device-to-device operation, the
communication device comprising: a receiver configured to receive
at least one signal from a controlling node of the cellular radio
access network for performing cell search; and a controller
configured to, when the communication device is in an out-of
coverage, OoC, state with relation to the controlling node, assign
a scheme for the cell searching such that the communication device
is configured to perform cell search according to a cell search
scheme where the controller is arranged to determine whether a D2D
operation is one of ongoing and imminent, wherein the communication
device is arranged to perform the cell search at a first rate when
no D2D operation is one of ongoing and imminent, and to perform the
cell search at a second rate when D2D operation is one of ongoing
and imminent, the first rate allows the communication device to
identify a cell within a first time period and the second rate
allows the communication device to identify a cell within a second
time period, where the first time period is larger than the second
time period.
19. The communication device of claim 18, wherein a time period
where the communication device identifies the cell within one of
the first and second time period is defined as a cell
identification delay.
20. A communication device for operating with a cellular radio
access network and configured for device-to-device operation, the
communication device comprising: a receiver configured to receive
at least one signal from a controlling node of the cellular radio
access network for performing cell search; and a controller
configured to, when the communication device is in an out-of
coverage, OoC, state with relation to the controlling node, assign
a scheme for the cell searching such that the communication device
is configured to perform cell search according to a cell search
scheme where the controller is arranged to determine whether a D2D
operation is one of ongoing and imminent, wherein the communication
device is arranged to perform the cell search at a first rate when
no D2D operation is one of ongoing and imminent, and to perform the
cell search at a second rate when D2D operation is one of ongoing
and imminent, the first rate and the second rate being used to
search a cell within a time duration equal to a first cell
identification delay and a second cell identification delay,
respectively.
21. A method of a communication device configured for cellular
communication and device-to-device, D2D, operation, the method
comprising: determining at the communication device, whether the
communication device is in one of an out-of-coverage, OoC, state
and in-coverage, IC, state in relation to a cellular radio access
network; performing cell search, when the communication device is
in the IC state, according to a first cell search scheme; and
performing cell search, when the communication device is in the OoC
state, according to a second cell search scheme, performing the
second cell search scheme comprising: determining whether a D2D
operation is one of ongoing and imminent; performing the cell
search at a first rate when no D2D operation is one of ongoing and
imminent; and performing the cell search at a second rate when D2D
operation is one of ongoing and imminent, the first rate and the
second rate being used to search a cell within a time duration
equal to a first cell identification delay and a second cell
identification delay, respectively.
22. The method of claim 21, wherein the first rate and the second
rate define how often information about a cell to be searched
should be received and processed.
23. The method of claim 22, wherein the first rate allows the
communication device to identify a cell within a first time period
and the second rate allows the communication device to identify a
cell within a second time period, where the first time period is
larger than the second time period.
24. The method of claim 23, wherein a time period where the
communication device identifies the cell within one of the first
and second time period is defined as a cell identification
delay.
25. The method of claim 21, further comprising, when it has been
determined that the D2D operation is ongoing: determining when the
D2D operation stops; starting a timer; and when the timer has
elapsed, returning to the determining whether a D2D operation is
one of ongoing and imminent.
26. The method of claim 21, wherein the second rate corresponds to
any of: a cell search rate used in the IC state; a discontinuous
reception, DRX, cycle; and a rate preconfigured by the radio access
network.
27. The method of claim 21, wherein the out of coverage state
comprises `any cell selection state`.
28. The method of claim 27, wherein the `any cell selection state`
is a type of radio resource control, RRC, state where the
communication device is preconfigurable to perform D2D operation on
a side link of a preconfigured carrier.
29. The method of claim 21, wherein D2D operation is at least one
of: D2D transmission; D2D reception; Proximity service, ProSe,
direct communication; and ProSe direct discovery.
30. The method of claim 21, wherein the first cell search scheme
comprises performing a cell search attempt at least one time per
100 ms.
31. A method of a communication device configured for cellular
communication and device-to-device, D2D, operation, the method
comprising: determining at the communication device, whether the
communication device is in one of an out-of-coverage, OoC, state
and in-coverage, IC, state in relation to a cellular radio access
network; performing cell search, when the communication device is
in the IC state, according to a first cell search scheme; and
performing cell search, when the communication device is in the OoC
state, according to a second cell search scheme, performing the
second cell search scheme comprising: determining whether a D2D
operation is one of ongoing and imminent; performing the cell
search at a first rate when no D2D operation is one of ongoing and
imminent; and performing the cell search at a second rate when D2D
operation is one of ongoing and imminent, the relation between the
first rate and the second rate being such that the second rate is
higher than the first rate by a scaling factor.
32. A method of a communication device configured for cellular
communication and device-to-device, D2D, operation, the method
comprising: determining at the communication device, whether the
communication device is in one of an out-of-coverage, OoC, state
and in-coverage, IC, state in relation to a cellular radio access
network; performing cell search, when the communication device is
in the IC state, according to a first cell search scheme; and
performing cell search, when the communication device is in the OoC
state, according to a second cell search scheme, the determining at
the communication device whether the communication device is in one
of an out-of-coverage, OoC, state and in-coverage, IC, state in
relation to the cellular radio access network comprising:
determining a physical layer metric based on at least one received
signal from the controlling node of the cellular radio access
network; and determining whether the cellular communication device
is one of in coverage and out of coverage of the controlling node
based on the physical layer metric.
33. A communication device for operating with a cellular radio
access network and configured for device-to-device operation, the
communication device comprising: a receiver configured to receive
at least one signal from a controlling node of the cellular radio
access network for performing cell search; and a controller
configured to determine whether the communication device is in one
of an out-of-coverage, OoC, state and in-coverage, IC, state with
relation to the controlling node, and assign a scheme for
performing the cell search such that the communication device is
configured to perform cell search, when the communication device is
in the IC state, according to a first cell search scheme, and to
perform cell search, when the communication device is in the OoC
state, according to a second cell search scheme, the controller is
configured to, upon performing the second cell search scheme,
determine whether a D2D operation is one of ongoing and imminent,
the communication device being arranged to perform the cell search
at a first rate when no D2D operation is one of ongoing and
imminent, and to perform the cell search at a second rate when D2D
operation is one of ongoing and imminent, the first rate and the
second rate being configured to be used to search a cell within a
time duration equal to a first cell identification delay and a
second cell identification delay, respectively.
34. The communication device of claim 33, wherein the controller is
configured to, upon performing the second cell search scheme,
determine whether a D2D operation is one of ongoing and imminent,
wherein the communication device is arranged to perform the cell
search at a first rate when no D2D operation is one of ongoing and
imminent, and to perform the cell search at a second rate when D2D
operation is one of ongoing and imminent.
35. The communication device of claim 34, wherein the first rate
and the second rate define how often information about a cell to be
searched should be received and processed.
36. The communication device of claim 35, wherein the first rate
allows the communication device to identify a cell within a first
time period and the second rate allows the communication device to
identify a cell within a second time period, where the first time
period is larger than the second time period.
37. The communication device of claim 36, wherein a time period
where the communication device identifies the cell within one of
the first and second time period is defined as a cell
identification delay.
38. The communication device of claim 33, wherein the controller is
further configured to, upon determination that the D2D operation is
ongoing, determine when the D2D operation stops, start a timer,
and, when the timer has elapsed, repeat the determination whether a
D2D operation is one of ongoing and imminent.
39. The communication device of claim 33, wherein the controller is
configured to determine whether the communication device is in one
of the out-of-coverage, OoC, state and in-coverage, IC, state in
relation to the cellular radio access network by being configured
to determine a physical layer metric based on at least one received
signal from the controlling node of the cellular radio access
network; and determine whether the cellular communication device is
one of in coverage and out of coverage of the controlling node
based on the physical layer metric.
40. The communication device of claim 33, wherein the first cell
search scheme comprises performing a cell search attempt at least
one time per 100 ms.
41. A communication device for operating with a cellular radio
access network and configured for device-to-device operation, the
communication device comprising: a receiver configured to receive
at least one signal from a controlling node of the cellular radio
access network for performing cell search; and a controller
configured to determine whether the communication device is in one
of an out-of-coverage, OoC, state and in-coverage, IC, state with
relation to the controlling node, and assign a scheme for
performing the cell search such that the communication device is
configured to perform cell search, when the communication device is
in the IC state, according to a first cell search scheme, and to
perform cell search, when the communication device is in the OoC
state, according to a second cell search scheme, the relation
between the first rate and the second rate being such that the
second rate is higher than the first rate by a scaling factor.
42. A method of a network node of a cellular radio access network
configured to communicate with a communication device configured
for cellular communication and device-to-device, D2D, operation,
the method comprising: determining information about a rate on
which the communication device is expected to perform cell search
when out-of-coverage in relation to the cellular radio access
network; and transmitting the information about the rate to the
communication device, the information comprising at least one of:
information about a first rate to the communication device on which
the communication device is expected to perform cell search when
out-of-coverage in relation to the cellular radio access network
and no D2D operation is one of ongoing and imminent; and
information about a second rate to the communication device on
which the communication device is expected to perform cell search
when out-of-coverage in relation to the cellular radio access
network and D2D operation is one of ongoing and imminent, the
relation between the first rate and the second rate being such that
the second rate is higher than the first rate by a scaling
factor.
43. The method of claim 42, wherein D2D operation is at least one
of: D2D transmission; D2D reception; Proximity service, ProSe,
direct communication; and ProSe direct discovery.
44. The method of claim 42, further comprising transmitting the
scaling factor to the communication device.
Description
TECHNICAL FIELD
The present invention generally relates to a method of a
communication device enabled for cellular communication and
device-to-device (D2D) communication. The present invention further
relates to a method of a network node, computer programs, a
communication device and a network node.
Abbreviations
Below are explanations of some of the abbreviations that may occur
in this disclosure. Other abbreviations are explained in connection
with their use in the text.
TABLE-US-00001 Abbreviation Explanation 3GPP Third generation
partnership program AP Access point BLER Block error rate BS Base
station BSC Base station controller BTS Base transceiver station
CGI Cell global identity CSI Channel state information DAS
Distributed antenna system DL Downlink DRX Discontinuous reception
eNodeB Evolved NodeB FDD Frequency division duplex LTE Long term
evolution M2M machine to machine MCG Master cell group MDT
Minimization of drive tests MeNB Master eNode B MME Mobility
management entity MSR Multi-standard radio PCI Physical cell
identity PCell Primary Cell PSS Primary synchronization signal RAT
Radio Access Technology RX Receiver RLM Radio link monitoring RNC
Radio Network Controller RRC Radio resource control RRH Remote
radio head RRU Remote radio unit RSRP Reference Signal Received
Power RSRQ Reference Signal Received Quality RSSI Received signal
strength indication RSTD Reference signal time difference RX
Receiver SCell Secondary Cell SCG Secondary Cell Group SeNB
Secondary eNode B SINR Signal to interference and noise ratio SNR
Signal to noise ratio SON Self-organizing networks SSS Secondary
synchronization signal TA Timing advance TDD Time division duplex
TX Transmitter UE User equipment UL Uplink
BACKGROUND
Radio measurements done by a communication device, such as a user
equipment (UE), are typically performed on the serving as well as
on neighbour cells over some known reference symbols or pilot
sequences. The measurements are done on cells on an intra-frequency
carrier, inter-frequency carrier(s) as well as on inter-RAT
carriers(s) (depending upon the UE capability whether it supports
that RAT). To enable inter-frequency and inter-RAT measurements the
network configures measurement gaps for the UE, which gaps may
comprise time/frequency where the serving cell performs no or
limited transmissions (e.g. almost blank subframes).
The measurements are done for various purposes. Some example
measurement purposes are to support in: mobility, positioning,
self-organizing networks (SON), minimization of drive tests (MDT),
operation and maintenance (O&M), network planning and
optimization etc. Examples of measurements in 3GPP Long Term
Evolution (LTE) are: Cell identification (which is also referred to
as PCI acquisition), RSRP, RSRQ, CGI acquisition, RSTD, UE RX-TX
time difference measurement, RLM, which comprises Out of
synchronization (out of sync) detection and In synchronization
(in-sync) detection etc. Channel State Information (CSI)
measurements performed by the UE are used for scheduling, link
adaptation etc. by network. Examples of CSI measurements or CSI
reports are Channel Quality Indicator (CQI), Precoding Matrix
Indicator (PMI), Rank Indicator (RI), etc. They may be performed on
reference signals like Cell-specific Reference Signal (CRS), CSI
Reference Signal (CSI-RS) or Demodulation Reference Signal
(DMRS).
In order to support different functions such as mobility (e.g. cell
selection, cell re-selection, handover, etc.), positioning a UE,
link adaption, scheduling, load balancing, admission control,
interference management, interference mitigation etc., the radio
network node, such as an eNode B, also performs radio measurements
on signals transmitted and/or received by the radio network node.
Examples of such measurements are SNR, SINR, received interference
power (RIP), BLER, propagation delay between UE and itself,
transmit carrier power, transmit power of specific signals (e.g. TX
power of reference signals), positioning measurements like TA,
eNode B RX-TX time difference etc.
For example in 3GPP LTE, the DL subframe #0 and subframe #5 carry
synchronization signals (i.e. both PSS and SSS). In order to
identify an unknown cell (e.g. new neighbour cell) the UE has to
acquire the timing of that cell and eventually the physical cell ID
(PCI). Subsequently the UE also measures RSRP and/or RSRQ of the
newly identified cell in order to use itself and/or report the
measurement to the network node. In total there are 504 PCIs in
3GPP LTE.
The UE searches or identifies a cell (i.e. acquires PCI of the
cell) by correlating the received PSS/SSS signals in DL subframe #0
and/or in DL subframe #5 with one or more of the pre-defined
PSS/SSS sequences e.g. combination of PSS and SSS sequences leading
to up to 504 cell identities in LTE. The use of subframe #0 and/or
in DL subframe #5 for PCI acquisition depends upon the UE
implementation. The UE may further correlate over cell specific
reference signals with the pre-defined CRS sequence(s) after the
detection of PSS/SSS. The UE regularly attempts to identify
neighbour cells on at least the serving carrier frequency(-ies).
But it may also search cells on non-serving carrier(s) when
configured by the network node. In order to save UE power
consumption, the UE typically searches in one of the DL subframes
#0 and #5. In order to further save its battery power the UE may
search the cell once every 40 ms in a non-DRX or in a short DRX
cycle (e.g. up to 40 ms). For longer DRX cycles the UE typically
searches a cell once every DRX cycle. During each cell search
attempt the UE typically stores a snapshot of 5-6 ms and
post-processes this by correlating the stored signals with the
known PSS/SSS sequences. In non-DRX the UE is able to identify an
intra-frequency cell (including RSRS/RSRQ measurements) within 800
ms (i.e. 20 attempts in total including 15 and 5 samples for cell
identification (PCI acquisition) and RSRP/RSRQ measurement).
In device-to-device (D2D) communication, the UEs transmit D2D
signals or channels in the uplink part of the spectrum. i.e. either
UL resources in TDD or on the UL carrier in FDD. D2D operation by a
UE is using a half-duplex mode, i.e. the UE can either transmit D2D
signals/channels or receive D2D signals/channels. There may also be
D2D UEs, acting as relay nodes, which may relay some signals to
other D2D UEs. There is also control information for D2D, some of
which are transmitted by D2D UEs and others transmitted by eNodeBs
(e.g., D2D resource grants for D2D communication transmitted via
cellular DL control channels). The D2D transmissions may occur on
resources which are configured by the network or selected
autonomously by the D2D UE.
D2D communication implies transmitting, by a D2D transmitter. D2D
data and D2D communication control information with scheduling
assignments (SAs) to assist D2D receivers of the D2D data. The D2D
data transmissions are transmitted according to configured
patterns, which may be defined by time and/or frequency, and in
principle may be transmitted rather frequently. SAs are transmitted
periodically. D2D devices that are within the network coverage may
request network node (e.g. eNodeB) resources for their D2D
communication transmissions and in response, receive D2D resource
grants for SA and D2D data. Furthermore, the network node (e.g.
eNodeB) may broadcast D2D resource pools, i.e. the time/frequency
assignments in response to the resource requests, for D2D
communication.
D2D discovery messages are transmitted in infrequent periodic
subframes. Network nodes (e.g. eNodeBs) may broadcast D2D resource
pools for D2D discovery, both for reception and transmission. The
D2D communication supports two different modes of D2D operation:
mode 1 and mode 2. In mode 1, the location of the resources for
transmission of the scheduling assignment by the broadcasting
wireless device (e.g UE) comes from the network node (e.g. eNodeB).
The location of the resource(s) for transmission of the D2D data by
the broadcasting UE comes from the eNodeB. In mode 2 a resource
pool for scheduling assignment is pre-configured and/or
semi-statically allocated. The UE on its own selects the resource
for scheduling assignment from the resource pool for scheduling
assignment to transmit its scheduling assignment.
PCell interruption of one subframe occurs when the UE switches its
reception from D2D to Wide Area Network (WAN) or from WAN to D2D.
This is because the UE receiver chain needs to be retuned every
time the operation is switched from WAN to D2D reception and from
D2D to WAN reception. This applies to both D2D discovery and D2D
communication capable UEs. It is important to partition uplink
resources between cellular uplink and D2D operation in such a way
that avoids or minimize the risk of switching taking place in
certain subframes, i.e. subframe #0 and/or #5, of the PCell. These
subframes contain essential information, such as PSS/SSS that are
necessary for doing cell search, carrying out cell measurements and
they also contain Master Information Block/System Information Block
(MIB/SIBI) information which is necessary for System Information
(SI) reading procedures. In addition to the interruption that takes
places due to switching, there may be additional interruption of
one subframe due to the RRC reconfiguration procedure. While the
switching interruption takes place for UE with a single receiver
(RX) (e.g. D2D discovery capable UEs), the RRC reconfiguration
interruption takes place for all types of D2D UEs (e.g. D2D
Discovery capable and D2D Communication capable UEs). Here, D2D
Discovery concerns the ability of devices to discover other devices
in their vicinity. The discovery may be network centric or device
centric. The purpose of the discovery may be to establish D2D
communication or merely to provide information to application
layer, for example for a social networking application, that
another device is in vicinity. The D2D Communication capability
concerns the capability to exchange data directly between devices
without going via a network node.
D2D operation is a generic term which may comprise of transmission
and/or reception of any type of D2D signals (e.g. physical signals,
physical channels etc.) by a D2D communication capable UE and/or by
D2D discovery capable UE. D2D operation is therefore also called
D2D transmission, D2D reception, D2D communication etc.
A D2D UE is also interchangeably called a Proximity Service (ProSe)
capable UE. D2D discovery capable UE is also referred to as UE
capable of ProSe direct discovery, and D2D (direct) communication
capable UE is also referred to as a UE capable of ProSe direct
communication. The radio link and radio carrier that is used for
the ProSe direct communication and ProSe direct discovery between
UEs is referred to as side link.
SUMMARY
The present disclosure is based on the realization that adapting
the cell search scheme when a communication device is out of
network coverage may save power in communication devices.
According to a first aspect, there is provided a method of a
communication device enabled for cellular communication and
device-to-device, D2D, communication and operating in an
out-of-coverage, OoC, state. The method comprises determining
whether a D2D operation is ongoing or imminent, performing cell
search according to a first rate when no D2D operation is ongoing
or imminent, and performing cell search according to a second rate
when D2D operation is ongoing or imminent.
The first rate and the second rate may define how often information
about a cell to be searched should be received and processed by the
communication device.
The relation between the first rate and the second rate may be such
that the second rate is higher than the first rate by a scaling
factor.
The first rate may correspond to that the communication device
identifies a cell within a first time period and the second rate
may correspond to that the communication device identifies a cell
within a second time period, where the first time period may be
larger than the second time period. A time period where the
communication device identifies the cell within the first or second
time period may be defined as a cell identification delay.
The first rate and the second rate may be used to search a cell
within a time duration equal to a first cell identification delay
and a second cell identification delay, respectively.
The method may comprise, upon determining that the D2D operation is
ongoing, determining when the D2D operation stops, starting a
timer, and when the timer having elapsed, returning to the
determining whether a D2D operation is ongoing or imminent.
The second rate may correspond to any of a cell search rate used in
an in-coverage, IC, state, a discontinuous reception, DRX, cycle,
and a rate preconfigured by the radio access network.
The out of coverage state may comprise `any cell selection state`.
The `any cell selection state` may be a type of radio resource
control (RRC) state where the communication device is
preconfigurable to perform D2D operation on a side link of a
preconfigured carrier.
The D2D operation may be any one or more of D2D transmission, D2D
reception. Proximity service (ProSe) direct communication, and
ProSe direct discovery.
According to a second aspect, there is provided a communication
device for operating with a cellular radio access network and
enabled for device-to-device communication. The communication
device comprises a receiver arranged to receive at least one signal
from a controlling node of the cellular radio access network for
performing cell search, and a controller arranged to, when the
communication device is in an out-of-coverage, OoC, state with
relation to the controlling node, assign a scheme for the cell
searching such that the communication device is arranged to perform
cell search according to a cell search scheme where the controller
is arranged to determine whether a D2D operation is ongoing or
imminent, wherein the communication device is arranged to perform
the cell search at a first rate when no D2D operation is ongoing or
imminent, and to perform the cell search at a second rate when D2D
operation is ongoing or imminent.
The first rate and the second rate may define how often information
about the cell should be received and processed.
The relation between the first rate and the second rate may be such
that the second rate is higher than the first rate by a scaling
factor.
The first rate may correspond to that the communication device
identifies a cell within a first time period and the second rate
may correspond to that the communication device identifies a cell
within a second time period, where the first time period may be
larger than the second time period. A time period where the
communication device identifies the cell within the first or second
time period may be defined as a cell identification delay.
The first rate and the second rate may be used to search a cell
within a time duration equal to a first cell identification delay
and a second cell identification delay, respectively.
The controller may be arranged to, upon determination that the D2D
operation is ongoing, determine when the D2D operation stops, start
a timer, and when the timer having elapsed, return to the
determination whether a D2D operation is ongoing or imminent.
The second rate may correspond to any of a cell search rate used in
an in-coverage, IC, state, a discontinuous reception (DRX) cycle,
and a rate preconfigured by the radio access network.
The out of coverage state may comprise `any cell selection state`.
The `any cell selection state` may be a type of radio resource
control (RRC) state where the communication device is
preconfigurable to perform D2D operation on a side link of a
preconfigured carrier.
The D2D operation may be any one or more of D2D transmission, D2D
reception, Proximity service (ProSe) direct communication, and
ProSe direct discovery.
According to a third aspect, there is provided a computer program
comprising instructions which, when executed by a processor of a
communication apparatus, causes the communication apparatus to
perform the method according to the first aspect.
According to a fourth aspect, there is provided a method of a
communication device enabled for cellular communication and
device-to-device (D2D) communication. The method comprises
determining, at the communication device, whether the communication
device is in an out-of-coverage (OoC) state or in-coverage (IC)
state with relation to a cellular radio access network, performing
cell search, when the communication device is in the IC state,
according to a first cell search scheme, and performing cell
search, when the communication device is in the OoC state,
according to a second cell search scheme.
The second cell search scheme may include determining whether a D2D
operation is ongoing or imminent, performing the cell search at a
first rate when no D2D operation is ongoing or imminent, and
performing the cell search at a second rate when D2D operation is
ongoing or imminent. The first rate and the second rate may define
how often information about a cell to be searched should be
received and processed by the communication device. The first rate
may correspond to that the communication device identifies a cell
within a first time period and the second rate may correspond to
that the communication device identifies a cell within a second
time period, where the first time period may be larger than the
second time period. A time period where the communication device
identifies the cell within the first or second time period may be
defined as a cell identification delay.
The first rate and the second rate may be used to search a cell
within a time duration equal to a first cell identification delay
and a second cell identification delay respectively.
The method may further comprise, when it has been determined that
D2D operation is ongoing, determining when the D2D operation stops,
and then starting a timer, and when the timer has elapsed,
returning to the determining whether a D2D operation is ongoing or
imminent.
The relation between the first rate and the second rate may be such
that the second rate is higher than the first rate by a scaling
factor. The scaling factor may be given by a function defining how
a kind or type of D2D operation activity of the ongoing or imminent
D2D operation is assigned in relation to that kind or type. The
function may for example be a mapping. The function may be such
that, when the kind or type of D2D operation activity of the
ongoing or imminent D2D operation is a discovery signalling, the
scaling factor is based on a periodicity of the discovery
signalling.
The method may comprise receiving information about the scaling
factor from the radio access network.
The second rate may correspond to any of a cell search rate used in
the IC state, a discontinuous reception, DRX, cycle, and a rate
preconfigured by the radio access network.
The out of coverage state may comprise `any cell selection state`.
Here, the `any cell selection state` is a term meaning that the
communication device has not found any acceptable cell, as for
example discussed in 3GPP TS 36.304 specification, version 8.10.0,
section 5.2.8 and in Figure 5.2.2-1. The `any cell selection state`
may be a type of radio resource control (RRC) state where the
communication device is preconfigurable to perform D2D operation on
a side link of a preconfigured carrier.
The D2D operation may be any one or more of D2D transmission, D2D
reception, Proximity service (ProSe) direct communication, and
ProSe direct discovery.
The determining at the communication device whether the
communication device is in OoC state or IC state in relation to the
cellular radio access network may comprise determining a physical
layer metric based on at least one received signal from the
controlling node of the cellular radio access network, and
determining whether the cellular communication device is in
coverage or out of coverage of the controlling node based on the
physical layer metric.
The first cell search scheme may comprise performing a cell search
attempt at least one time per 100 ms.
According to a fifth aspect, there is provided a communication
device for operating with a cellular radio access network and
enabled for device-to-device communication. The communication
device comprises a receiver arranged to receive at least one signal
from a controlling node of the cellular radio access network for
performing cell search, and a controller arranged to determine
whether the communication device is in an out-of-coverage (OoC)
state or in-coverage (IC) state with relation to the controlling
node and assign a scheme for the cell searching such that the
communication device is arranged to perform cell search, when the
communication device is in the IC state, according to a first cell
search scheme, and to perform cell search, when the communication
device is in the OoC state, according to a second cell search
scheme.
The controller may be arranged to, upon the second cell search
scheme, determine whether a D2D operation is ongoing or imminent,
wherein the communication device may be arranged to perform the
cell search at a first rate when no D2D operation is ongoing or
imminent, and to perform the cell search at a second rate when D2D
operation is ongoing or imminent. The first rate and the second
rate may define how often information about the cell should be
received and processed. The first rate may correspond to that the
communication device identifies a cell within a first time period
and the second rate may correspond to that the communication device
identifies a cell within a second time period, where the first time
period may be larger than the second time period. A time period
where the communication device identifies the cell within the first
or second time period may be defined as a cell identification
delay.
The first rate and the second rate may be configured to be used to
search a cell within a time duration equal to a first cell
identification delay and a second cell identification delay,
respectively.
The controller may be arranged to, upon determination that the D2D
operation is ongoing, determine when the D2D operation stops, start
a timer, and, when the timer has elapsed, repeat the determination
whether a D2D operation is ongoing or imminent.
The relation between the first rate and the second rate may be such
that the second rate is higher than the first rate by a scaling
factor.
The controller may be arranged to determine whether the
communication device is in the OoC state or IC state in relation to
the cellular radio access network by being arranged to determine a
physical layer metric based on at least one received signal from
the controlling node of the cellular radio access network, and
determine whether the cellular communication device is in coverage
or out of coverage of the controlling node based on the physical
layer metric.
The first cell search scheme may comprise performing a cell search
attempt at least one time per 100 ms.
According to a sixth aspect, there is provided a computer program
comprising instructions which, when executed by a processor of a
communication apparatus, causes the communication apparatus to
perform the method according to the fourth aspect.
According to a seventh aspect, there is provided a method of a
network node of a cellular radio access network enabled to
communicate with a communication device enabled for cellular
communication and device-to-device (D2D) communication. The method
comprises determining information about a rate on which the
communication device is expected to perform cell search when
out-of-coverage in relation to the cellular radio access network
and transmitting the information about the rate to the
communication device. The information comprises at least one of
information about a first rate to the communication device on which
the communication device is expected to perform cell search when
out-of-coverage in relation to the cellular radio access network
and no D2D operation is ongoing or imminent, and information about
a second rate to the communication device on which the
communication device is expected to perform cell search when
out-of-coverage in relation to the cellular radio access network
and D2D operation is ongoing or imminent.
The D2D operation may be any one or more of D2D transmission, D2D
reception, Proximity service (ProSe) direct communication, and
ProSe direct discovery.
The relation between the first rate and the second rate may be such
that the second rate is higher than the first rate by a scaling
factor. The method may comprise transmitting the scaling factor to
the communication device.
The information about the first and second rates may comprise the
second rate, and a scaling factor for a relation between the first
rate and the second rate wherein the second rate is higher than the
first rate by the scaling factor. The scaling factor may be given
by a function defining how a kind or type of D2D operation activity
of the ongoing or imminent D2D operation is assigned in relation to
that kind or type. The function may for example be a mapping. The
function may be such that, when the kind of D2D operation activity
of the ongoing or imminent D2D operation is a discovery signalling,
the scaling factor is based on a periodicity of the discovery
signalling.
According to an eighth aspect, there is provided a network node of
a cellular radio access network enabled to communicate with a
communication device enabled for cellular communication and
device-to-device, D2D, communication. The network node comprises a
controller, and a transmitter. The controller and transmitter are
arranged to determine and transmit out-of-coverage parameters
regarding cell search for the communication device according to the
seventh aspect.
According to a ninth aspect, there is provided a computer program
comprising instructions which, when executed by a processor of a
network node, causes the network node to perform the method
according to the seventh aspect.
BRIEF DESCRIPTION OF THE DRAWINGS
The above, as well as additional objects, features and advantages
of the present invention, will be better understood through the
following illustrative and non-limiting detailed description of
embodiments of the present invention, with reference to the
appended drawings.
FIG. 1 schematically illustrates the principles for D2D
communication within LTE.
FIG. 2 is a flow chart illustrating a method according to an
embodiment.
FIG. 3 is a flow chart illustrating procedures for the second cell
search scheme according to an embodiment.
FIG. 4 illustrates a time line and events according to an
example.
FIG. 5 is a block diagram schematically illustrating a device or
communication device according to an embodiment.
FIG. 6 schematically illustrates a computer-readable medium and a
processing device.
FIG. 7 illustrates a wireless network comprising a network node and
a communication device.
DETAILED DESCRIPTION
D2D operation in out of network coverage (ONC) or out-of-coverage
(OoC) is a new scenario where a D2D UE may operate also when no
access network coverage is present. An example is a UE used for
public safety which should be able to communicate directly with
other public safety UEs also when no access network coverage is
present. D2D UEs can be pre-configured with ProSe resources that
the UEs use when they are out of network coverage. Examples of
ProSe resources are ProSe subframes, time slots, physical channels
such as resource blocks within ProSe subframes or time slots etc.
These pre-configured resources are intended to be used only in an
out of network coverage scenario. If they are used inside the cells
of the cellular network or in close proximity of those cells. D2D
UEs may cause interference and harm the cellular communication in
the cells. To further minimize interference during ProSe operation
in an ONC or OoC scenario, the D2D UEs can further be configured
with one or more parameters associated with the pre-configured
ProSe resources. These parameters ensure that UE operates with
reduced power and lowers emissions in carriers outside that of the
side link. Examples of these parameters associated with ProSe
resource parameters are P-Max-ProSe and
additionalSpectrumEmissions-ProSe. Here, P-Max-ProSe is a parameter
defining the maximum power of ProSe transmissions when operating
out-of-coverage, and the parameter
additionalSpectrumEmissions-ProSe is used by the D2D UE to adjust
its transmission to meet region-specific regulatory emission
requirements when the D2D UE is operating out-of-coverage. D2D UE
behaviour on how the pre-configured ProSe resources shall be
controlled when a new cell has been detected is not defined. Due to
lack of specified UE behaviour and corresponding performance
requirements, the use of ProSe resources by the D2D UE when it
enters inside the network coverage may cause interference to the
WAN i.e. where one or more WAN cells are operating and can receive
signals from the D2D UE. Hence a ProSe UE using D2D transmission in
out of coverage needs to quickly detect whether it comes into
coverage of a network (NW) node, hence cell search needs to be
performed often.
However doing cell searches too often is costly in terms of power
and battery life and hence it is not desirable to have "always on"
approach w.r.t cell search all the time when the UE is
out-of-coverage. Therefore there is a need for an approach on how a
D2D wireless communication device or ProSe UE should perform
intra-frequency cell search when in an out of coverage
scenario.
In this description the terms device, communication device,
wireless device, UE, D2D device or ProSe UE may be used, but may in
general be any device, sensor, smart phone, modem, laptop, Personal
Digital Assistant (PDA), tablet, mobile terminal, smart phone,
laptop embedded equipped (LEE), laptop mounted equipment (LME),
Universal Serial Bus (USB) dongles, machine type UE. UE capable of
machine to machine (M2M) communication, etc.
In some embodiments a generic terms "network node" or "controlling
node" are used and it can correspond to any type of radio network
node or any network node, which communicates with a wireless device
(e.g. a ProSe UE or UE) and/or with another network node. Examples
of network nodes are NodeB, MeNB, SeNB, a network node belonging to
MCG or SCG, base station (BS), multi-standard radio (MSR) radio
node such as MSR BS, eNodeB, network controller, radio network
controller (RNC), base station controller (BSC), Cluster Head,
relay, donor node controlling relay, base transceiver station
(BTS), access point (AP), transmission points, transmission nodes,
RRU, RRH, nodes in distributed antenna system (DAS), core network
node (e.g. Mobile Switching Centre (MSC), Mobility Management
Entity (MME), etc.), O&M, Operations and Support Systems (OSS),
SON etc.
The communication device (e.g. a UE or ProSe UE or D2D device) is
able to connect to a cellular system (LTE for instance) and may be
able to direct communication to another ProSe UE (in a D2D
communication) on a subset of the cellular system frequency
resources (UL resources for instance). The resources for ProSe
operation are used on an UL carrier (e.g. UL subframes on UL
carrier) in FDD or half duplex FDD or on UL resources (e.g. UL
subframes) in TDD. The cellular system is also interchangeably
called a wireless access network (WAN) system.
FIG. 1 shows the principles for D2D communication within LTE.
Although LTE is shown for this embodiment, other embodiments may
work with other wireless technologies. A controlling node 100, i.e.
eNode B or Cluster Head, is controlling the communication on a
frequency carrier f_0. In a first scenario, devices A and B are
communicating directly via a D2D link, and both devices are inside
NW coverage of the controlling node. The controlling node then
allocates the radio resources to use for D2D communication. In the
second scenario devices C and D may have D2D communication outside
coverage of a controlling node. In this case the D2D communication
is using pre-configured (e.g. by a standard specification, or by
device capabilities) frequency/time (f/t)-resources for D2D
communication. Since the pre-configured resources may be used by
other devices inside controlling node coverage, for example a
device E which is communicating with the controlling node, the D2D
communication between devices C and D may start to interfere with
the communication between device E and the controlling node, if
devices C and D are coming into the controlling node coverage. It
is thus also desired that a device can detect in a controlled way
whether it is coming inside network coverage, in order to minimize
the risk for interference.
In order to know whether the device is In (network) Coverage (IC)
or Out of (network) Coverage (OoC), the device may have a physical
layer metric in order to determine the coverage state, since
different procedures and protocols are defined for transmission of
a discovery beacon, i.e. for D2D discovery, and D2D communication
when IC and OoC, i.e. start D2D operation or transmission without a
grant from the controlling node. A D2D operation may be any one or
more of D2D transmission, D2D reception, Proximity service (ProSe)
direct communication and Proximity service (ProSe) direct
discovery. The ProSe direct communication may further comprise
transmission and/or reception of signals related to ProSe.
In LTE, devices in RRC_connected mode, i.e. in active mode, and
served by a controlling node such as an eNodeB, are required to do
Radio Link Monitoring (RLM) on the physical layer in order to
detect whether the device is in-synchronization (in-sync) or
out-of-synchronization (out-of-sync) with respect to the serving
cell. RLM is performed using Down-Link (DL) Common Reference
Signals (CRS) and based on an estimated Signal-to-Interference
Ratio (SIR) which is mapped to a hypothetical Physical Downlink
Control CHannel (PDCCH) BLER. The mapping may be a function of
antenna and system bandwidth configurations. Based on the estimated
PDCCH BLER, the device determines in-sync or out-of-sync on the
physical layer, which determination then is reported to higher
layer for further action. If Radio Link Failure (RLF) is declared
at the higher layer, the device then returns to idle mode (e.g.
RRC_IDLE state). The RLM is used for several purposes, for instance
detection of whether the device goes out of network coverage, but
also gives a controlled way for the device to go back to idle mode
(e.g. RRC_IDLE state) in case synchronization is lost, due to some
internal device sync problem, or due to, for instance, a failure of
a handover process (between two controlling nodes). In the latter
two cases, the RLF declaration is made even if the device still may
be inside network coverage.
A first approach may be to try to reuse the RLM for D2D operation
for detecting whether the device is IC or OoC. However, several
problems may be envisioned by reusing this out-of-sync definition
for OoC detection in relation to D2D communication, for
instance:
1. In case of internal problem or malfunction of the device or a
handover failure, the device need not to be in OoC even if RLF is
declared, and hence, without proper OoC definition, the device may
start using pre-configured D2D resources, which then may introduce
significant interference within the cell.
2. The RLF is only defined in RRC_connected mode, hence a device
OoC as well as in RRC_idle will not perform RLM.
3. A conventional LTE device may have an internal, specific NW
coverage definition, in order to enable optimized cell search etc.
in order to reduce the power consumption.
Hence, to avoid these problems there is a need to know whether a
communication device is in IC or OoC. This may be inherent
knowledge, e.g. from other processed of the communication device,
or be determined. This issue is discussed for example in WO
2015/063185. In brief, WO 2015/063185 suggests that a physical
layer metric should be determined based on at least one potentially
received signal from a controlling node of the cellular radio
access network, and based on the physical layer metric it should be
determined whether the cellular communication device is in coverage
or out of coverage of the controlling node. For example, a state or
value associated with the metric may be considered, e.g. by
comparing the value with a threshold and/or mapping the state to
whether the cellular communication device is in coverage or out of
coverage of the controlling node, wherein the physical layer metric
may comprise a Random Access Response received from the controlling
node, and the state associated with the metric comprises whether
the Random Access Response is received or not. For example, the
cellular communication device is determined to be in coverage of
the controlling node if the Random Access Response was received
within a predetermined number of Random Access attempts. The
physical layer metric may alternatively comprise a synchronisation
signal or a pilot signal received from the controlling node and
filtered over a predetermined time, and the value associated with
the metric may comprise a signal level or
signal-to-noise-and-interference-ratio of the synchronisation
signal or pilot signal, and the cellular communication device is
determined to be in coverage of the controlling node if the signal
level or signal-to-noise-and-interference-ratio is above the
threshold. Another approach may be based on that the physical layer
metric comprises a broadcast signal received from the controlling
node, and the state associated with the metric comprises whether
the broadcast signal is decodable or not, wherein the cellular
communication device for example may be determined to be in
coverage of the controlling node if the broadcast signal was able
to be decoded within a predetermined time interval. Alternatively,
the physical layer metric comprises a control channel received from
the controlling node, and the state associated with the metric
comprises whether the control channel is decodable or not.
FIG. 2 is a flow chart illustrating a method of a communication
device according to an embodiment. Coverage status of the
communication device towards a network node, i.e. whether the
device (e.g. a UE or ProSe UE) is in IC or OoC, is analysed or
monitored 1, which may be performed as discussed above or will be
discussed in greater detail below. Depending on the outcome of the
analysis 1, it is determined 2 whether the device is considered to
be OoC or not. If the device is not OoC, i.e. IC, cell search is
performed 3 according to a first cell search scheme. This first
cell search scheme may resemble or be equal to an ordinary cell
search scheme for a device connected to or camping on a cell. If
the device is determined to be in OoC, cell search is performed 4
according to a second cell search scheme. The second cell search
scheme may be adapted, in view of the first cell search scheme,
such that energy and/or power consumption is reduced in the
device.
The first cell search scheme resembles and ordinary cell search
scheme for a cellular communication device. Thus, the communication
device regularly searches for cells, e.g. every 40 or 80 ms.
FIG. 3 is a flow chart illustrating procedures for the second cell
search scheme. It is to be noted that the OoC monitoring procedure
as demonstrated with reference to FIG. 2 may be running in
parallel, i.e. according to a real-time principle, wherein the
procedure demonstrated here with reference to FIG. 3 may be
interrupted and a switch to the first cell search scheme may be
made, e.g. based on the outcome of cell search and its processing,
may be made anywhere in the procedure illustrated in FIG. 3.
Since FIG. 3 illustrates procedures according to the second cell
search scheme, it is assumed that the device (e.g. a UE or ProSe
UE) is considered to be OoC. The communication device determines
300 whether a D2D operation is ongoing or imminent. This is given
by inherent knowledge at the communication device of D2D traffic.
If no D2D operation is ongoing or imminent, the device will perform
302 cell search at a first rate. The rate is how often the device
will attempt to detect a new cell. For example, a rate of one cell
detection attempt per 40 ms means that device will attempt to
detect a new cell once every 40 ms. This first rate will be
arranged to be below a threshold (e.g. below one attempt per 100
ms) to save energy and/or power, as will be further discussed
below. If a D2D operation is ongoing or imminent, the device will
perform 304 a cell search at a second rate. The second rate may be
higher than the first rate, and since communication is or will be
ongoing anyway, there is not as much energy or power to save to
keep the second rate low. The energy saving is mainly achieved by
keeping the first rate low in comparison to the second rate.
The approach for the second cell search scheme demonstrated above
will be running as the device is in OoC. However, at intermittent
D2D traffic being fairly intensive, there may be frequent shifts
between the first and second rates. To avoid such ping-pong effect,
the procedure may optionally include checking 305 whether a D2D
operation has stopped or halted. If not, i.e. the D2D communication
is still ongoing, the cell search continues using the second rate
and the monitoring 305 whether a D2D operation has stopped or
halted goes on. If the D2D communication has stopped or halted, a
timer may be started 307 and the procedure continues performing
cell search at the second rate until the timer has elapsed 309.
Then the procedure returns to the checking 300 whether a D2D
operation is ongoing or imminent, and so on. By this optional
approach, some hysteresis is formed such that switching to the
first cell search rate for very short intermediate periods is
avoided. FIG. 4 illustrates how this may work.
FIG. 4 illustrates a time line and events in OoC according to an
example. FIG. 4 illustrates a time line with D2D operations
indicated at the top of the time line, and the cell search rates is
indicated below the time line. At first, in this example, the
device performs cell search at the first rate. Then, as a D2D
operation starts, the device changes to perform cell search at the
second rate. When the D2D operation ends, the timer starts and when
the timer has elapsed it is checked whether a D2D operation is
ongoing or imminent. In the example of FIG. 4 it is not, and the
device changes to perform cell search at the first rate. After a
while, D2D operations start again, and the device changes to
performing cell search at the second rate. When this D2D operation
ends, the timer is started again and when the timer has elapsed, it
is again checked whether a D2D operation is ongoing or imminent.
Here, when the timer is on, there is an ongoing D2D operation, and
the device continues to make cell search at the second rate. Thus,
the first rate may correspond to that the communication device
identifies a cell within the first time period and the second rate
may correspond to that the communication device identifies a cell
within the second time period, where the first time period may be
larger than the second time period. For example, the first time
period may be in the magnitude of 30 seconds and the second time
period may be in the magnitude of 5 seconds.
An advantage is thus power saving by the applied first and second
rates, as demonstrated above. A particular advantage of this power
saving is realized when considering for example the application to
for example public safety UEs.
A device, such as a D2D capable device (D2D device or D2D UE), may
monitor whether the device is in-coverage or out of coverage w.r.t
to a serving cell using a frequency band supporting D2D
communication, with respect to which cell (i.e. the serving cell)
the device is out of coverage. The OoC may also interchangeably be
called as out-of-network coverage (ONC), out of WAN coverage, out
of cellular coverage, any cell selection state etc. The OoC or any
cell selection state may be a type of RRC state where the UE can be
preconfigured to perform D2D operation on a side link of a
preconfigured carrier. In this scenario, D2D devices communicating
with each other are not under network coverage. Therefore the D2D
devices in OoC cannot receive signals from and/or transmit signals
to any network node in the network. Typically the lack of coverage
is due to complete absence of the network coverage in the vicinity
of the D2D devices, due to which the D2D devices cannot use timing
and frequency synchronization based on signals from any cell in the
network.
The monitoring may be performed by the device by doing cell search
on a cell on a DL carrier or DL resources used for that frequency
band according to one or more existing procedures or device
implementation e.g. by correlating the received PSS/SSS signals
with their pre-defined values in LTE.
The device (e.g. UE) coverage status (e.g. OoC or IC) with respect
to a cell (e.g. current serving cell) may be determined by the
device by comparing a signal measurement (e.g. RSRP in LTE) with
one or more thresholds. The device may also compare a plurality of
signal measurements (e.g. RSRP, SINR. BLER, SNR, RSRQ, CQI etc in
LTE) performed by the device with their respective thresholds for
determining in coverage or OoC status of the device with respect to
its serving cell. In certain embodiments, for example, the out of
network coverage (OoC) may be determined by the device when the
signal measurement (e.g. RSRP in LTE) indicates a received signal
level below a first threshold that may correspond to a possibility
for reliable detection of broadcast information and/or or certain
control channels e.g. PDCCH in LTE systems. In other embodiments,
the OoC is determined based on whether broadcast information (MIB
and D2D relevant SIBs) transmitting in one or more broadcast
channels (e.g. Physical Broadcast CHannel (PBCH), Physical Downlink
Shared Channel (PDSCH), etc.) may be possible to be reliably
detected. The device may assume that the information is reliably
detected if the signal quality of the channels is within an
acceptable range (e.g. BER or BLER is below a BER/BLER threshold,
SNR is above SNR threshold etc). In yet another embodiment, the OoC
status of the device is detected based on not receiving any network
response, which sometimes is referred to as random access response
(RAR) on Random Access transmissions by the device. Another
approach for a device determining whether it is OoC is also
disclosed in WO2015/063185, as discussed above.
In case a control unit in the device indicates in-coverage, the
device may be considered to be in NW coverage and hence cell search
may be performed according to a first cell search scheme at a rate,
i.e. how often information, for determining information about the
cell should be received and processed. The first cell search scheme
may use a cell search scheme according to an ordinary scheme for
devices being connected to or camping on a cell, as discussed
above. For instance, if the wireless device is in idle mode, cell
search is made, i.e. a new cell is tried to be detected, according
to a rate such that a new cell can be detected within 32 seconds
for a DRX cycle of 1.28 seconds.
In case the control unit determines that the wireless device is
OoC, according to one or more metrics and/or requirements or
conditions as discussed above, the device performs cell search on a
cell belonging to a first carrier, associated with a second carrier
carrying UL resources (one or more side-links) used for D2D
operation (e.g. D2D communication and/or D2D discovery) according
to a first rate. The cell search rate or cell detection rate herein
means how often the wireless device performs cell search, e.g. how
often the wireless device performs correlation over the received
synchronization signals (e.g. PSS/SSS) with one or more pre-defined
synchronization sequences. The second carrier may be the same as
the first carrier, for example in TDD, or in case of FDD or half
duplex FDD it may be an UL carrier and first carrier a DL carrier.
The first rate may be similar to the rate needed in case the UE is
in-coverage and in RRC idle mode. As an example the UE may detect
the cell on the first carrier once every DRX cycle or with a rate
such that a new cell becoming stronger than a threshold, for
instance SINR of -6 dB (aka ratio of received energy to total
received interference and noise (Es/lot) of -6 dB), should be
detected and verified via RSRP measurements within 32 seconds
assuming DRX cycle of 1.28 seconds. The embodiments herein cover
also other first rates as well as detection requirements e.g. time
to detect the cell using the first rate. The requirements can be
specified in a standard.
The first rate may be explicitly pre-defined, e.g. to perform
search cell once every second or once every DRX cycle, or it may be
implicitly pre-defined to be corresponding to the rate in RRC idle
state or in connected state for certain DRX cycle, e.g. DRX cycle
of 1.28 s, or it may also be preconfigured by a network node, e.g.
by previous serving cell and information of the rate is transmitted
from the network node to the communication device.
A processing element or control unit in the device continuously
monitors whether the device is going to initiate, enable or start
D2D operations e.g. D2D transmissions, or knows that such D2D
operations are ongoing. As long as no D2D operation, e.g. D2D
transmission, is started, the device continues to do cell search on
the first carrier. The wireless device determines if it is
performing or will start D2D operation or transmission in one or
more of several ways based on one or more estimations or
measurements. Example embodiments may be that the wireless device
determines D2D activity, i.e. that D2D operation is ongoing or
imminent, if a buffer containing D2D data for transmission is
non-empty or if a radio control unit enables the radio transmitter
to start a D2D transmission or if the radio transmitter measures or
detects that signals are being transmitted in any D2D resource,
etc. Once such determination is made that there is D2D activity or
D2D activity is expected to start on a side-link, then the wireless
device performs cell search on a cell on a first carrier, which is
associated with a second carrier carrying UL resources. i.e. the so
called side-link used for D2D communication, according to a second
rate.
The second rate may be similar to the rate needed in case of
in-coverage active mode, e.g. for RRC_connected in LTE, i.e. every
40 ms, or with a rate such that a signal from a new cell becoming
stronger than a first threshold, for instance -6 dB for Es/lot,
should be detected and verified via RSRP measurements within 800
ms. Other second rates as well as detection requirements are
equally feasible. The control unit monitors the D2D operation and
as long as there are ongoing D2D sessions the cell search continues
to be performed according to the second rate. In some embodiments,
once the D2D operation has stopped, the rate for cell search is
changed back to the first rate. In other embodiments the change or
transition back to the first rate is made after an inactivity timer
has expired, which may be set to for example 1-5 seconds. The timer
may be enabled once D2D operation has stopped/halted. A benefit of
this is that ping-pong effects between transitions of first and
second rates are avoided. In yet another embodiment the cell search
at the second rate is continued also during D2D operation and the
inactivity timer is enabled once the D2D operation is halted, and
then a change to first rate is made once the timer expires.
The first and/or the second rates may also be explicitly
pre-defined, e.g. to perform search cell once every 40 ms or once
every DRX cycle, e.g. assuming DRX of 80 ms or shorter, or the
rate(s) may be implicitly pre-defined to be corresponding to the
cell search rate used by the device in connected state for certain
DRX cycle, e.g. DRX cycle of 40 ms, or the rate(s) may also be
preconfigured by a network node, e.g. by previous serving cell.
As an example, the first and the second rates may be defined such
that the communication device is required to identify a cell:
within X seconds based on the first rate when no D2D operation is
ongoing or not imminent and within Y seconds based on the second
rate when D2D operation is ongoing or imminent, where X is larger
than Y. Examples of X and Y are 30 seconds and 5 seconds
respectively. In another example, X and Y can be 20 seconds and 1
second respectively. In another example, the first and the second
rates may be defined as being associated with first and second cell
identification delays (aka cell detection delays, cell search
delays etc.). The cell detection rate and the cell identification
delay may be related. The cell identification delay is the time or
duration over which the device identifies or detects a cell using a
particular rate. For example when using the first rate the device
will detect the cell during the first cell identification delay.
Also for example when using the second rate the device will detect
the cell during the second cell identification delay. These delays
may be defined such that the communication device identifies a
cell: within P seconds when no D2D operation is ongoing or not
imminent, and within Q seconds when D2D operation is ongoing or
imminent, where P is larger than Q.
In yet another example, the first rate (R1) and the second rate
(R2) as well as the first (P) and the second (Q) cell
identification delays may be pre-defined. The second rate and the
first rate may be associated by a relation or a function, which may
be pre-defined or configured by the network node, or it may be
determined by the UE autonomously. Typically the second rate is
higher than the first rate for detecting a cell on the first
carrier. For example, a relation or function associating the second
rate (R2) and the first rate (R1) may be expressed as:
R2=f(R1,.mu.i), [1]
where .mu.i is a scaling factor, which may be pre-defined or
configured by the network node. The scaling factor, .mu.i, may in
turn be a function of for example a communication state of the D2D
operations.
A specific example of the relation between the first and second
rates is: R2=.mu.1*R1, [2]
where .mu.1 is a scaling factor. Different values of the scaling
factor may be applied in different situations or under different
criteria such as speed of the device, frequency band of the carrier
on which cell is to be detected, type of D2D operation, such as
ProSe direction communication or direct discovery etc., e.g.
R2=.mu.2*R1 for one situation [3] R2=.mu.3*R1 for another
situation, and [4] R2=.mu.4*R1 for still another situation. [5]
The scaling factors may for example be determined by experimenting,
e.g. performing simulations, for the different situations to tune
operation, and/or by considering particulars of communication for
the situation.
The second and the first cell identification delay (or cell
detection delay, cell search delay etc.) may also be associated by
a relation or a function, which may be pre-defined or configured by
the network node, or it may be determined by the UE autonomously.
The second cell identification delay may be shorter than the first
cell identification delay for detecting a cell on the first
carrier. For example, a relation or function associating the second
rate cell identification delay (D2) and the first cell
identification delay (D1) may be expressed as: D2=f(D1,.beta.i)
[6]
where .beta.1 is a scaling factor, which may be pre-defined or
configured by the network node. The scaling factor, .beta.i, may in
turn be a function of for example, a communication state of the D2D
operations. A specific example of the relation between the first
and second cell identification delays is: D2=.beta.1*D1 [7]
where .beta.1 is a scaling factor. Different values of the scaling
factor may be applied in different situations or under different
criteria such as speed of the device, frequency band of the carrier
on which cell is to be detected, type of D2D operation, such as
ProSe direction communication or direct discovery etc, e.g.
D2=.beta.2*D1 for one situation [8] D2=.beta.3*D1 for another
situation, and [9] D2=.beta.4*D1 for still another situation.
[10]
The relation between the first rate and the second rate or between
the first and the second cell identification delays may also depend
upon the type of D2D operation performed by the device or the D2D
wireless device. One scaling factor (or function) may be used for
general transmitting, another for general receiving, still another
for discover signals, still further another for some special known
transmission pattern, etc. The scaling factor for respective
communication state may then be adapted such that the rates
correspond to respective communication pattern wherein energy
consumption may be further decreased. For example, for the case of
discovery signals, the rates may be adapted to the periodicity of
the discovery signals. For general transmitting and/or receiving,
the scaling factor may for example be based on some statistics on
previously performed operations.
The second carrier frequency on whose slide link the wireless
device performs D2D operation in OoC may: be the carrier of the
last serving cell before the wireless device entered in the OoC
i.e. last or previous intra-frequency carrier; or it may be a
separate carrier preconfigured with D2D resources for D2D operation
in OoC. For example the carrier frequency, on which the device can
perform D2D operation when the device goes in OoC (or any cell
selection state), is preconfigured by the last serving cell. The
preconfigured carrier can be the same carrier as the carrier of the
last serving cell or it can be a different carrier frequency.
In case the wireless device is configured for D2D operations on
side links of multiple carriers, e.g. on carriers for PCell, SCell,
etc. in carrier aggregation, or last intra-frequency carrier and
carrier configured for D2D operation in OoC, then the wireless
device may also perform the cell search procedure when in OoC, as
described above, to detect cells on all the carriers i.e. on the
corresponding downlink carriers. In this case the wireless device
may use the same sets of the first and second rates for detecting
cells on all carriers. In another embodiment the wireless device
may use different sets of the first and second rates for detecting
cells on different carriers. The first and second rates and/or
their relations may be pre-defined, configured by the network node
and corresponding information transmitted to the device or
autonomously decided by the wireless device.
In case the wireless device detects any cell on the first carrier
frequency or on any carrier in case of multiple carriers, then the
wireless device may stop performing D2D operation or stop
performing a certain type of D2D operation e.g. stop transmitting
D2D signals.
FIG. 5 is a block diagram schematically illustrating a device or
communication device 500 according to an embodiment. The
communication device comprises or is associated with an antenna
arrangement 502, a receiver 504 connected to the antenna
arrangement 502, a transmitter 506 connected to the antenna
arrangement 502, a processing element or controller 508 which may
comprise one or more circuits, one or more input interfaces 510 and
one or more output interfaces 512. The interfaces 510, 512 can be
user interfaces and/or signal interfaces, e.g. electrical or
optical. The communication device 500 is arranged to operate in a
cellular communication network, as demonstrated above. In
particular, by the processing element 508 being arranged to perform
the embodiments demonstrated with reference to FIGS. 1 to 4, the
communication device 500 is capable of communication within a 3GPP
LTE network, and in particular LTE direct communication, i.e. D2D
communication. The processing element 508 can also fulfil a
multitude of tasks, ranging from signal processing to enable
reception and transmission since it is connected to the receiver
504 and transmitter 506, executing applications, controlling the
interfaces 510, 512, etc. In particular, the communication device
500 is arranged for operating with a cellular radio access network
and enabled for device-to-device communication. The receiver 504 is
arranged to receive at least one potential signal, i.e. a signal
that might be received considering that we here discuss
out-of-coverage, OoC, scenarios, from a controlling node of the
cellular radio access network for performing cell search. The
processing element 508 may implement one or more controllers
arranged to determine whether the communication device 500 is in an
OoC, state or in-coverage, IC, state with relation to the
controlling node 100 and assign a scheme for the cell searching and
perform a cell search according to what has been demonstrated
above. Thus, the processing element 508 may be referred to as "a
controller 508", as indicated above, when considering that
functionality. The processing element 508 may comprise a
determining unit 514 arranged to analyse a coverage status of the
device and to determine whether the communication device 500 is in
an out-of-coverage, OoC, state or in-coverage, IC, state with
relation to the controlling node 100. The processing element may
further comprise at least one cell search unit 516 arranged to
assign a scheme for the cell searching and perform a cell search
according to what has been demonstrated above.
Returning to FIG. 1, the controlling node 100 may be a network node
of a cellular radio access network enabled to communicate with the
communication devices which may be enabled for cellular
communication and device-to-device, D2D, communication. The network
node comprises a controller, and a transmitter. The controller and
transmitter are arranged to determine and transmit out-of-coverage
parameters regarding cell search for the communication device. The
determination and transmitting may comprise information about the
first rate preconfigured by the radio access network to the
communication device on which the communication device is expected
to perform cell search when out-of-coverage and no D2D operation
(e.g. a transmission) is ongoing or imminent. The determination and
transmitting may also comprise information about the second rate
preconfigured by the radio access network to the communication
device on which the communication device is expected to perform
cell search when out-of-coverage and D2D operation is ongoing or
imminent. The information about the first and second rates may be
provided such that it comprises the second rate and a scaling
factor for a relation between the first rate and the second rate
wherein the second rate is higher than the first rate by the
scaling factor. The scaling factor may be given by a function
defining how a kind or type of D2D operation activity of the
ongoing or imminent D2D operation is assigned in relation to that
kind or type. The function may for example be a mapping. The
function may for example be such that, when the kind of D2D
operation activity of the ongoing or imminent D2D operation is a
discovery signalling, the scaling factor is based on a periodicity
of the discovery signalling. Other functions, as demonstrated
above, for adapting to the current D2D situation, may also be
provided. By the scaling factor or scaling factor function, and
information about one of the rates, the communication device may
determine the rates to be used. A corresponding method for the
network node, and a computer program for implementing the method in
the network node are thus provided accordingly.
The methods disclosed herein may be suitable for implementation
with aid of processing means, such as computers and/or processors,
especially for the case where the processing element 508
demonstrated above comprises a processor handling cell search
schemes. Therefore, there is provided computer programs, comprising
instructions arranged to cause the processing means, processor, or
computer to perform the steps of any of the methods according to
any of the embodiments described above.
FIG. 6 schematically illustrates a computer-readable medium and a
processing device. The computer programs may comprise program code
which is stored on a computer readable medium 600, as illustrated
in FIG. 6, which can be loaded and executed by a processing means,
processor, or computer 602 to cause it to perform the methods,
respectively, according to embodiments of the present invention,
preferably as any of the embodiments described above. The computer
602 and computer program product 600 can be arranged to execute the
program code sequentially where actions of the any of the methods
are performed stepwise. The processing means, processor, or
computer 602 may be what normally is referred to as an embedded
system Thus, the depicted computer readable medium 600 and computer
602 in FIG. 6 should be construed to be for illustrative purposes
only to provide understanding of the principle, and not to be
construed as any direct illustration of the elements. The
illustration of FIG. 6 is applicable for computer program, computer
readable-medium and processing device for both the communication
device and the network node according to different embodiments
demonstrated herein.
FIG. 7 illustrates a wireless network comprising a more detailed
view of a network node 200 and a communication device 210, in
accordance with a particular embodiment. For simplicity, FIG. 7
only depicts network 220, network nodes 200 and 200a, and
communication device 210. Network node 200 comprises processor 202,
storage 203, interface 201, and antenna 201a. Similarly, the
communication device 210 comprises processor 212, storage 213,
interface 211 and antenna 211a. These components may work together
in order to provide network node and/or wireless device
functionality. In different embodiments, the wireless network may
comprise any number of wired or wireless networks, network nodes,
base stations, controllers, wireless devices, relay stations,
and/or any other components that may facilitate or participate in
the communication of data and/or signals whether via wired or
wireless connections.
Network 220 may comprise one or more IP networks, public switched
telephone networks (PSTNs), packet data networks, optical networks,
wide area networks (WANs), local area networks (LANs), wireless
local area networks (WLANs), wired networks, wireless networks,
metropolitan area networks, and other networks to enable
communication between devices.
Network node 200 comprises processor 202, storage 203, interface
201, and antenna 201a. These components are depicted as single
boxes located within a single larger box. In practice however, a
network node may comprises multiple different physical components
that make up a single illustrated component (e.g., interface 201
may comprise terminals for coupling wires for a wired connection
and a radio transceiver for a wireless connection). Similarly,
network node 200 may be composed of multiple physically separate
components (e.g., a NodeB component and a RNC component, a BTS
component and a BSC component, etc.), which may each have their own
respective processor, storage, and interface components. In certain
scenarios in which network node 200 comprises multiple separate
components (e.g., BTS and BSC components), one or more of the
separate components may be shared among several network nodes. For
example, a single RNC may control multiple NodeB's. In such a
scenario, each unique NodeB and BSC pair, may be a separate network
node. In some embodiments, network node 200 may be configured to
support multiple radio access technologies (RATs). In such
embodiments, some components may be duplicated (e.g., separate
storage 203 for the different RATs) and some components may be
reused (e.g., the same antenna 201a may be shared by the RATs).
Processor 202 may be a combination of one or more of a
microprocessor, controller, microcontroller, central processing
unit, digital signal processor, application specific integrated
circuit, field programmable gate array, or any other suitable
computing device, resource, or combination of hardware, software
and/or encoded logic operable to provide, either alone or in
conjunction with other network node 200 components, such as storage
203, network node 200 functionality. For example, processor 202 may
execute instructions stored in storage 203. Such functionality may
include providing various wireless features discussed herein to a
wireless devices, such as WD 210, including any of the features or
benefits disclosed herein.
Storage 203 may comprise any form of volatile or non-volatile
computer readable memory including, without limitation, persistent
storage, solid state memory, remotely mounted memory, magnetic
media, optical media, random access memory (RAM), read-only memory
(ROM), removable media, or any other suitable local or remote
memory component. Storage 203 may store any suitable instructions,
data or information, including software and encoded logic, utilized
by network node 200. Storage 203 may be used to store any
calculations made by processor 202 and/or any data received via
interface 201.
Network node 200 also comprises interface 201 which may be used in
the wired or wireless communication of signalling and/or data
between network node 200, network 220, and/or WD 210. For example,
interface 201 may perform any formatting, coding, or translating
that may be needed to allow network node 200 to send and receive
data from network 220 over a wired connection. Interface 201 may
also include a radio transmitter and/or receiver that may be
coupled to or a part of antenna 201a. The radio may receive digital
data that is to be sent out to other network nodes or WDs via a
wireless connection. The radio may convert the digital data into a
radio signal having the appropriate channel and bandwidth
parameters. The radio signal may then be transmitted via antenna
201a to the appropriate recipient (e.g., WD 210).
Antenna 201a may be any type of antenna capable of transmitting and
receiving data and/or signals wirelessly. In some embodiments,
antenna 201a may comprise one or more omni-directional, sector or
panel antennas operable to transmit/receive radio signals between,
for example, 2 GHz and 66 GHz. An omni-directional antenna may be
used to transmit/receive radio signals in any direction, a sector
antenna may be used to transmit/receive radio signals from devices
within a particular area, and a panel antenna may be a line of
sight antenna used to transmit/receive radio signals in a
relatively straight line.
WD 210 may be any type of communication device, wireless device,
UE, D2D device or ProSe UE, but may in general be any device,
sensor, smart phone, modem, laptop. Personal Digital Assistant
(PDA), tablet, mobile terminal, smart phone, laptop embedded
equipped (LEE), laptop mounted equipment (LME), Universal Serial
Bus (USB) dongles, machine type UE, UE capable of machine to
machine (M2M) communication, etc., which is able to wirelessly send
and receive data and/or signals to and from a network node, such as
network node 200 and/or other WDs. WD 210 comprises processor 212,
storage 213, interface 211, and antenna 211a. Like network node
200, the components of WD 210 are depicted as single boxes located
within a single larger box, however in practice a wireless device
may comprises multiple different physical components that make up a
single illustrated component (e.g., storage 213 may comprise
multiple discrete microchips, each microchip representing a portion
of the total storage capacity).
Processor 212 may be a combination of one or more of a
microprocessor, controller, microcontroller, central processing
unit, digital signal processor, application specific integrated
circuit, field programmable gate array, or any other suitable
computing device, resource, or combination of hardware, software
and/or encoded logic operable to provide, either alone or in
combination with other WD 210 components, such as storage 213, WD
210 functionality. Such functionality may include providing various
wireless features discussed herein, including any of the features
or benefits disclosed herein.
Storage 213 may be any form of volatile or non-volatile memory
including, without limitation, persistent storage, solid state
memory, remotely mounted memory, magnetic media, optical media,
random access memory (RAM), read-only memory (ROM), removable
media, or any other suitable local or remote memory component.
Storage 213 may store any suitable data, instructions, or
information, including software and encoded logic, utilized by WD
210. Storage 213 may be used to store any calculations made by
processor 212 and/or any data received via interface 211.
Interface 211 may be used in the wireless communication of
signalling and/or data between WD 210 and network node 200. For
example, interface 211 may perform any formatting, coding, or
translating that may be needed to allow WD 210 to send and receive
data from network node 200 over a wireless connection. Interface
211 may also include a radio transmitter and/or receiver that may
be coupled to or a part of antenna 211a. The radio may receive
digital data that is to be sent out to network node 201 via a
wireless connection. The radio may convert the digital data into a
radio signal having the appropriate channel and bandwidth
parameters. The radio signal may then be transmitted via antenna
211a to network node 200.
Antenna 211a may be any type of antenna capable of transmitting and
receiving data and/or signals wirelessly. In some embodiments,
antenna 211a may comprise one or more omni-directional, sector or
panel antennas operable to transmit/receive radio signals between 2
GHz and 66 GHz. For simplicity, antenna 211a may be considered a
part of interface 211 to the extent that a wireless signal is being
used.
In some embodiments, the components described above may be used to
implement one or more functional modules used in D2D communication.
The functional modules may comprise software, computer programs,
sub-routines, libraries, source code, or any other form of
executable instructions that are run by, for example, a processor.
In general terms, each functional module may be implemented in
hardware and/or in software. Preferably, one or more or all
functional modules may be implemented by processors 212 and/or 202,
possibly in cooperation with storage 213 and/or 203. Processors 212
and/or 202 and storage 213 and/or 203 may thus be arranged to allow
processors 212 and/or 202 to fetch instructions from storage 213
and/or 203 and execute the fetched instructions to allow the
respective functional module to perform any features or functions
disclosed herein. The modules may further be configured to perform
other functions or steps not explicitly described herein but which
would be within the knowledge of a person skilled in the art.
Certain aspects of the inventive concept have mainly been described
above with reference to a few embodiments. However, as is readily
appreciated by a person skilled in the art, embodiments other than
the ones disclosed above are equally possible and within the scope
of the inventive concept. Similarly, while a number of different
combinations have been discussed, all possible combinations have
not been disclosed. One skilled in the art would appreciate that
other combinations exist and are within the scope of the inventive
concept. Moreover, as is understood by the skilled person, the
herein disclosed embodiments are as such applicable also to other
standards and communication systems and any feature from a
particular figure disclosed in connection with other features may
be applicable to any other figure and or combined with different
features.
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